1. Field of the Invention
The invention relates to a method for fabricating a nitride semiconductor optical device, particularly the method for forming the air media layer within the nitride semiconductor optical device.
2. Description of the Prior Art
As for the structure of nitride semiconductor embedded with the air media layer, the light field can be confined in the nitride semiconductor material with high refractive index through the air media with low refractive index. Furthermore, the E-beam lithography is used to define the micro-structure on the nitride surface to form the micro resonance cavity in the nitride material. Its optical characteristics are studied through the different structural design of nitride. Due to the chemical property of nitride semiconductor is stable, it is difficult to remove the bottom semiconductor material to form nitride semiconductor thin film by the wet etching method. In the conventional art, different nitride material is used as the material of sacrificial layer. The optical chemical oxidization etching reaction is used to remove the nitride in the sacrificial layer. However, the etching rate and homogeneity of optical chemical oxidization etching reaction are not good, it is apt to cause uneven surface and even cause the structural defect or the drop of device characteristics.
Though the match between the nitride and the nitride semiconductor is well known, the lattice constant between them is very close, thus they are perfect match basically. However, it is still necessary to pay attention to the crystal quality of heterogeneous epitaxy. Therefore the invention discloses how to grow high-quality nitride and improve the heterogeneous structure of oxide.